The ability to monitor signaling pathways in live cells in real time will provide a new experimental methodology for identifying and assessing modulators of signal transduction cascades. The objective of this proposal is to produce, functionalize, and verify the utility of a new type of protein and peptide conjugated nanoparticle reporter that will readily traverse the plasma membrane, concentrate in the cytoplasm and be responsive to signal transduction events. Signaling events will be detected in real-time by optically tracking the translocation of the fluorescent signal transduction domain conjugated nanoparticles to specific, signal dependent intracellular locations. In Phase II we will expand the assay to allow multiplex analysis of the regulation of cell signaling proteins in real-time will provide insight regarding the interplay of signaling cascades and provide a source for unique biosensors. These biosensors will be immediately relevant for assessing exposure to potential chemical or biological threat agents, identifying toxic substances, and discovering novel modifiers of cell signaling pathways. The tools developed in this Phase I proposal will aid medical researchers in their understanding of complex biological systems, thus providing opportunities for the development of new diagnostic or therapeutic compounds.